1. Field of the Invention:
The invention relates to the manufacture of 2-propyn-1-ol (propargyl alcohol, HC.tbd.CCH.sub.2 OH) by catalytic decomposition of 2-butyn-1,4-diol.
2. Discussion of the Background:
2-Propyn-1-ol is used for synthesis of polyenes and other natural substances, and is also employed as a corrosion protection agent in electroplating. In the manufacture of 2-butyn-1,4-diol from formaldehyde and acetylene, 2-propyn-1-ol occurs as a minor byproduct.
In the known methods for manufacturing 2-propyn-1-ol, the starting materials are also formaldehyde and acetylene. The secondary reaction of 2-propyn-1-ol with formaldehyde to form 2-butyn-1,4-diol is suppressed by special reaction conditions.
In Ger. Pat. No. 11 74 765, addition of N-methylpyrrolidone to the reaction mixture is claimed. N-methylpyrrolidone is a good solvent for acetylene, thereby enabling a high acetylene concentration. The reaction of acetylene and formaldehyde in the presence of copper acetylide under the conditions stated leads principally to 2-propyn-1-ol. However, a substantial amount of 2-butyn-1,4-diol is formed. The cost of isolating pure 2-propyn-1-ol from the reaction mixture is high.
According to Ger. Pat No. 1,284,964, acetylene and formaldehyde can be reacted in a solvent, e.g. butyrolactone, with the aid of copper acetylide on a support, to form 2-butyn-1,4-diol and 2-propyn-1-ol. The two products are formed in comparable amounts. High acetylene pressures are used, which necessitates major expenditures on safety, particularly when large scale apparatus is employed.